1. Field of the Invention
The present invention relates to a wireless local loop. In particular, the present invention relates to a procedure for limiting the mobility or usability of a terminal device in a wireless local loop environment, as defined in the preamble of claim 1.
2. Description of Related Art
In a wireless local loop (WLL), a terminal device is connected via a radio link to an access node. Between the terminal device and the access node there is a base station, by means of which the call signals received via radiocommunication from the terminal device are further transmitted through the access node to the public telephone network and vice versa. The access node is connected to the telephone exchange using the V5.2 protocol. The mobility area (MOA) of a terminal device is a geographic area within which the terminal device may be connected to a wireless local loop and outside which the terminal device cannot be connected to the local loop. The mobility area defines the mobility area of a terminal device within the wireless network comprised by an access node. Mobility of a terminal device between the access nodes of a WLL operator is inhibited because subscriber information is only defined in a single access node. A terminal device cannot be locked with a public GSM network because the WLL operator has its own network identifier and no roaming agreement with GSM operators.
Open interfaces (V5.1 and V5.2) between an access node and a telephone exchange are defined in the ETSI (European Telecommunications and Standards Institute) standards of the ETS 300 324 and ETS 300 347 series. V5 interfaces enable subscribers belonging to a physically separate local loop to be connected using the standard interface of a telephone exchange. A dynamic concentrator interface V5.2 consistent with the standards ETS 300 347-1 and 347-2 consists of one or more (1-16) PCM (Pulse Code Modulation) cables. One PCM cable comprises a total of 32 channels, each of which with a transfer rate of 64 kbit/s, i.e. 2048 kbit/s in all. The V5.2 interface supports analogue telephones as used in the public telephone network, digital subscriptions, such as ISDN (Integrated Services Digital Network) basic and system subscriptions as well as other analogue or digital terminal equipment based on semi-fixed connections.
There are prior-art wireless telephone networks, an example of which is the digital GSM mobile telephone network, in which voice or sound signals or other corresponding data are transmitted using systems based on the ISDN (Integrated Services Digital Network) technology. In the GSM mobile telephone system, a terminal device may work in the entire area of the network, i.e. the terminal device may get locked, perform channel changes and other actions in the area of any cell. However, in a wireless local loop environment, a desired feature is the ability to accurately determine, e.g. via actions by the network operator, the area in which a mobile terminal device connected to the system via a wireless link can be used. A problem with prior-art networks is that the mobility area cannot be delimited. A further problem is that current systems provide no means for delimiting the mobility area for each individual terminal device.